I would like to start by saying this is an addition to my much older theory history of the Ark/Forerunner/Covies/Man a theory of my which has not changed at all. But this section is added to it. Since it practically can stand alone on its own, i decided to post it alone instead of reposting the orignal because that would look like an attempt to revive a dead thread. However, this was written as a part of the theory, so confusions or doubts that arise from my assumed facts are because those facts were explained else were in the theory, which why i suggest reading it first found http://forums.bungie.org/halo/archive22.pl?read=661112

THE TRUTH ABOUT THE PROPHET OF TRUTH

For those of you who are expecting me to reveal a logical plan for Truth’s conspiracy you will be sadly disappointed.

While the Prophet of Truth’s actions may seem suspicious to some, we are only looking from our stand point. The problem is, we can’t base a suspicious if we don’t know the normal course or pattern of the covenant society. Suspicion arises when something doesn’t quite fit. However, because only Bungie knows everything about the covenant culture, only they could see if something doesn’t fit. I am about to show you an example of how this can be true.

The entire covenant religion is based around the great journey. But what is it exactly. From most of the quotes we have heard, the great journey is religiously linked with death and halo. However, is the great journey really the covenant afterlife?

There is one famously important quote I would like to bring up.
(“No, Arbiter! The Great Journey has begun! And the Brutes, not the Elites, shall be the Prophets' escort!”)
Think for a minute.
-What is the title of this level? The Great Journey.
-What is Tartarus doing? Activating the ring.
-What is Truth doing? He is traveling to earth, (location of ark) on board a forerunner ship.
-What is another related word for travel? Journey.
-Lastly, Who do you think is piloting/on board this ship? Elites or Brutes? Brutes, due to recent events.

The covenant worship the forerunner, and they placed a Forerunner ship at the heart of there holiest city. This suggests that the forerunner ship had great meaning to the covenant. Let’s look back at the misinterpretation that leads to the beginning of the covenant.
Image the original forerunner phrase as After halo killed all life in the galaxy, the ark began its journey to reseed life in the galaxy. You must go out and reclaim all that we have lost. [remember, this message and planet was intended for humanity]

Well now here is my idea of how the prophets misread it. Halo kills all life and the journey of the ark turned into halo’s activation guides us in the great journey to the ark were life reborn (which turns to the great divine) “I shall light this sacred ring, release it's cleansing flame, AND BURN A PATH INTO THE DIVINE BEYOND!” Halos activation is supposed to reveal a path to the divine beyond. Without this path, you can not get to the divine beyond. The divine beyond is the covenant afterlife/utopia. And reclaim everything turns to claim everything. But then what is the Great Journey?

The Great Journey is the act of traveling this path into the divine beyond. Spiritually, this path is burned so brightly that the souls of the dead can follow it into the divined beyond. (Which is why when ever someone dies, they are referred to as beginning the great Journey. There soul has been placed onto the path, and now they just await for it to be lit up so they can see and follow it. Also “the weight of your heresy will stay your feet and you will be left behind.” This could be referring to that only faith allows on to move along the path and that heresy takes away your ability to move. ) Right now Truth is traveling in the great forerunner ship, being escorted by brutes. While one lights up the path by activating the ring.

Now here is the interesting part. Since halo has only ever been activated once in its life time, no one other than the sentinels, monitors, and flood know what halo looks like when it goes off. Truth does not know that Tartarus has failed. In fact, the only covenant that know halo failed to go off are the ones who were standing in the control room. So only the few elites and few brutes know it failed. And soon the SpecOpts commander will be informed, and as well the brutes reinforcements surrounding the area. Meanwhile, that pretty light show will have convinced the rest of the covenant it has begun. But has happen? Due to halo failing to go off, a message was set to all other rings putting them into standby mode to await remote activation. Is it not probably that a message would also be set to the ark to prepare for remote activation. Or at least, a transmission link between the ark and rings created. And by a twist of cruel irony, Truth takes this transmission to the ark as the path to the divine beyond, and thusly follows it. So, Truth thinks the Tartarus has been successful because a path has appeared leading to a already religious spot (earth, which is religious to the covenant some how because that’s why Regret went there looking for more forerunner stuff, and also learned the location of delta halo there) The Prophet of Truth is really following the covenant religion blindly and to its fullest extent. And all because every thing is playing out to make it seem true.

Q&A

Q: Why does Truth leave Mercy to die?
A: Truth already gave his answer. “The great journey awaits no one.” Truth is in a rush because the great journey is about to start. Being the highest prophets, it is extremely important that the prophet be on time for the one most important event in all of the religion. (Imagine if the pope got tied up with waiting for coworkers while judgment day was about to start)

With mercy’s dying words he said “earth, to finish want was started, and this time none of you will be left behind.” That “you” refers to/includes humans. So clearly this must be some conspiracy to kill of somebody.

Not if Mercy is true to his name, just like Regret is and how I support Truth is too. To finish what was started is referring to the quest to get into the divine beyond where the forerunners are. Yes, the you does refer/include humanity, but I think this is a general “you” referring to everyone, humanity, elites, etc. Now you might think this just supports killing everyone even more but wait. “And this time” means that this has to have happen before. Thusly I say he is referring to the activation of halo. However, remember, according to the covenant religion, what did the first activation of halo do. It brought the forerunner and all those worthy into the Divine Beyond. Thusly, that means, everyone else currently alive, the prophets, brutes, humans, grunts etc. were left behind during that first activation due to the fact that we are here and not in the divine beyond. And now, the Prophet of Mercy, being true to his name, is giving all races including humanity pardon and stating that they will not be left behind from the great journey and divine beyond. So despite the fact that master chief is the demon, always merciful Mercy is giving him pardon too. (Thanks Mercy but I think I will pass on your offer.)
My proof supporting this claim is in the name, Mercy, to say that Mercy is not saying mercy but instead, killing everyone for selfish cause goes against his name which isn’t just given to him for no reason.

clicky linking for the full theory if you are still confused, or interested.